Typewriting machine



Feb. 6, 1940. w. F. HELMOND TYPEWRITING MACHINE Filed May 12, 1938 INVENTOR W/LL/AM EHELMOND ATTORNEY Patented Feb. 6, 1940 PATENT oFFicE TYPEWRITING MACHINE- William F. Hclmond, West Hartford, Conn, 35- Signor to Underwood Elliott Fisher Company, New York, N. Y., a corporation of Delaware Application'May 12, 1938, Serial No. 207,558

. 2 Claims.

The present invention relates to keys for typewriters and similar machines.

Itis the general object of the invention to provide a typewriter key of such simple construction as to effect appreciable economies in its manufacture, although the key affords an easy touch for the fingers of the typist and provides'readily visible character indicla therewith.

The typewriter key constructed in accordance with the invention may include a base or keycup having means for attachment to a key-lever stem of the typewriter, the key-cup presenting a recess or cavity bordered by an upstanding cup- I rim, within which a character-bearing disk may be pressed to maintain itsprop'er position, the disk being'crowded' into the cup and. preferably against the bottom of same. The typewriter key may further include a transparent top disk pref erably of glass preformed in spherical contour and mounted on the cup-rim to present a concave face at the top of the key, being retained in place as by a key-cap having an inturned flange seated in a peripheral recess of the top disk and flush with its-concave face.

Thetypewriter key of the invention may, therefore, comprise a minimum nmnber of elements, each adapted for economic manufacture and facilitating rapid assembly. For instance, the novel key structure accommodates a cheaplyfabricated character disk which may be made in complete sets for one typewriter, all the required characters being printed simultaneously on a single sheet of stock, the individual disks, bearing the respective characters, being out out in one operation.

It is desired to equip the typewriter key with a transparent top-disk of concave form to assure an easy finger touch and it is also, desired, for

' the reasons above indicated, to employ a character-bearing and spaced from the top-disk. In a typewriter key so organized, the concave top-disk may produce a slightly distorted image of the type-character, particularly when viewed from the position normally taken by the typ-ist. The invention therefore contemplates further improveients in the form of the type-characterswhich in effect serve to correct the otherwise distorted image thereof, so that the character appears to the operator in its true form, notwithstanding the distorting cifectof the concave top-disk.

Other features and advantages will hereinafter appear.

The present invention is in the nature of an improvement over one shownin my co-pending to the interior of the cup-rim isk disposed within the key-cup application, Serial No. 702,301, filed December 14, 1933, now Patent No.- 2,118,846, issued May 31, 1938.

I In the accompanying drawing:

Figure 1 is'a perspective view of the assembled It typewriter key.

Figure 2 is an enlarged central vertical section through the typewriter key.

Figure 3 is an exploded perspective View illustrating the respective parts of the key, and

Figure 4 is a plan View of the improved character disk showing the normal and the corrective form of the type-character thereon.

Referring now to the drawing for a more detailed description thereof, the numeral 6 indi- 11b; cates the usual typewriter key-lever stem upon which a base or key-cup 1-. is affixed, the latter having a socket 8 fitting over the stem 6'. The key-cup '1 includes a bottom wall 9 and upstanding peripheral rim H defining-a cylindrical go recess or cavity H of substantial depth Within the cup "I. I A disk l2 formed. of sheet stock,v such as heavy paper or cardboard, has a suitable type character applied on its upper face, see Figure 3, the disk l2 being shaped to conform substantially It, and being slightly oversize relatively thereto so that it may be pressed firmly or crowded into the rim Ill to abut against the bottom wall 9 of the key-cup to be held against rotation therein and thus maintain alignment of the type-character in proper reading position. The character disk It may be economically fabricated as afore described, that is, by printing all of the disks required for the typewriter, on one sheet of stock, in a complete set, the individual disks bearing the respective characters being cut from the sheet simultaneously by punching or die-cutting in one operation. 1 The typewriter keymay include a top-disk l3 of transparent material, preferably glass so asto avoid surface scratching in use, and is preferably preformed in spherical contour to present a concave upper face. The top-disk 3, for economy, may be fabricated in accordance with the process shown and described in my aforesaid co-pending application, new Patent No. 2,118,846. The topdisk i3 is mounted on the key-cup l to rest upon the top edge of the cup-rim iii thereof. It is to 1 be noted here that due to the substantial depth of the key-cup l, the top-disk I3 is spaced from, and out of contact with the character disk l2 and therefore obviates the necessity otherwise, for constructing the mentioned elements accurately in size, particularly as to thickness, it being apu parent that each of the said disks l2, l3 may vary appreciably in thickness, and the top-disk l3 may vary in curvature, without adversely affecting the composite key structure.

The top-disk I3 is retained in place by a keycap l5 having an inturned flange or brim I6 engaging the disk l3. The periphery of disk 13 is undercut or otherwise for-med to provide a recess l'i' in which the cap-flange i6 is seated so that the latter is substantially flush with the upper face of the disk IS. The key-cap l5 may fit snugly over the periphery of the cup-rim l0 and is suitably secured thereto as by bendable lugs l9 integral with the key-cap l5 and clinched under the bottom wall 9 of the keycup I.

The use'of a concavo-convex or spherical form for the top-disk l3 in spaced relation to the character disk 52 produces an image of the type character which is somewhat distorted from the orig- 'inal on the disk l2 particularly when viewed from a position normally assumed by the typist. Such an illusion, although very slight, may be considered objectionable in some cases, and accordingly the invention is further directed to obviate thisoptical efiect on the type character. The distortion appears aggravated in such type characters as the letter H, having straight parallel members forming the complete letter. In such letters the spherically shaped top disc produces an image of the normally shaped letter'that is somewhat barrel-shaped and which, in effect, makes the extremities of the letter appear to converge toward each other. To counteract this condition, the characters are printed in a corrective form illustrated, for example, in Figure 4 by the letter The full line showing represents the corrective form of the letter as same is printed on the disk which so compensates for the distortion effected by the spherical disk that, when same is viewed in the assembled .key, the letter presents an image in the natural form as shown in dotand-dash outline in Figure 4.

It will therefore be seen that the improved type-key construction attains appreciable advantages of economy in manufacture and afiords highly desirable characteristics in use, also obviating any objectionable optical effect that may I be had by the arrangement of a lens-like top disk, with a type-character in. spaced relation below same. r

What is claimed is:

1. A key for use with a typewriter or the like, comprising in combination, a key-cup adapted for mounting as on a key-lever and presenting a peripheral rim defining a deep cylindrical recess, a disk havinga type character on one face crowded into the cylindrical recess against the bottom, thereof, a spherically formed transparent topdisk resting on said cup-rim in spaced relation to said character disk and presenting a concave flange overlying a border of said top-disk, surrounding said key-cup and secured thereto, said 20 upper face, and a key-cap having an inturned to said character disk and presenting a concave 7 upper face, and a key-cap having an inturned flange overlying a border of said top-disk, surrounding said key-cup and secured thereto, said type character having a form in which portions of the character converge toward each other in a corrective form to thereby counteract the distorting effect of said spherical top-disk so as to 0 present a character image in normal form to the view of the operator.

' WILLIAM F. HELMOND. I 

